Chosen Solution
Hey, I’m having this problem after i replaced the loudspeaker since the volume was very low. This didn’t solve the problem until i poked small holes into the loudspeaker mesh. Now whenever someone texts or calls me while vibration is activated, the phone reboots. While receiving the message or call the ringing sound is followed by a loud distorted electrical cracking sound. Today i replaced the lightning port but this also didn’t solve the problem. Update (04/28/2018) I recorded the problem. The Youtube Link is https://youtu.be/fnOvfy-rI0c|here.]
If you changed the loud speaker and it’s making a crackling noise I would suggest going back to the old loud speaker and see if this helps, I think the new load speaker could be faulty causing excessive battery drain causing restart. If this does not fix try iOS update then new battery
